A California jury decided on Wednesday that Michael Jackson’s final concert promoter, A.E.G. Live, was not responsible for the pop star’s death.

After a five-month trial filled with gruesome details of Jackson’s last days, the case came down to basic questions of contractual relationships and the professional competence of Dr. Conrad Murray, the cardiologist who gave Jackson a fatal dose of the anesthetic propofol four years ago.

After deliberating for about 13 hours over four days, the jury of six men and six women agreed with lawyers for Jackson’s 83-year-old mother, Katherine, that A.E.G. Live had hired Dr. Murray. But they rejected arguments that the doctor was unfit to care for Jackson as he prepared for a series of comeback concerts.

The verdict saves A.E.G. Live, the world’s second-largest concert company after Live Nation Entertainment, from paying what could have been huge damages. Lawyers for Mrs. Jackson, who filed the wrongful death lawsuit with the star’s three young children, sought up to $1.5 billion, most of that based on estimates of what Jackson could have earned had he lived and continued his career.

Jackson died on June 25, 2009, just weeks before the concerts were to have begun.

Marvin S. Putnam, A.E.G. Live’s lawyer, said in a statement that the verdict had confirmed “what we have known from the start — that although Michael Jackson’s death was a terrible tragedy, it was not a tragedy of A.E.G. Live’s making.”

After being tried for months in a small room at Los Angeles Superior Court, with no cameras allowed, the case was moved for its denouement to the court’s largest space, and the verdict was televised live. Mrs. Jackson, who attended the trial almost every day, left the courtroom quickly after the verdict was read, without making any statement.

For five months, two contrasting portraits of Jackson competed in the courtroom. In one, the singer of “Thriller” and “Billie Jean” was the victim of a compromised doctor and a callous, greedy promoter. The other version of Jackson was one of a drug abuser in an inevitable tailspin who cannily shopped for compliant doctors and deceived nearly everyone around him.

Over more than 80 days of testimony, each side in the case used evidence of Jackson’s demise against the other.

Jurors were shown photographs of Jackson’s naked corpse on an autopsy table, and witnesses described the star as chronically missing rehearsals and sometimes appearing dazed and emaciated. A paramedic who came to Jackson’s rented home in Los Angeles after a 911 call the morning he died said that Jackson had been so pale and thin that he assumed the star was a hospice patient “at the end of a long disease process.”

Lawyers for Jackson’s mother argued that A.E.G. Live was responsible for Dr. Murray and portrayed the company as ruthlessly driven by profit. In embarrassing e-mails shown repeatedly during the trial, A.E.G. Live executives mocked Jackson as “the freak” and appeared to play down a flurry of health concerns raised by concert staff members in the weeks before he died.

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Alif Sankey, a choreographer on the London shows, testified that one day shortly before Jackson died, he said he was talking to God. Worried about his frail physical and mental condition, she said, she called Kenny Ortega, the director, and begged him to intervene.

On the stand, Mrs. Jackson said tearfully that A.E.G. Live had “watched him waste away.”

Mrs. Jackson’s suit centered on whether her son or A.E.G. Live was responsible for hiring and supervising Dr. Murray, who was convicted of involuntary manslaughter two years ago and is serving a prison sentence.

A.E.G. Live portrayed Jackson as a superstar version of a classic drug abuser who went to any lengths necessary for drugs to alleviate his chronic pain and help him sleep. The company “never would have agreed to finance this tour if it knew Michael Jackson was playing Russian roulette every night in his bedroom,” Mr. Putnam said in his closing statement.

To portray Jackson’s downfall as one of his own making, the company called doctors and nurses who said that the singer had asked them for propofol; when they refused to comply, and told Jackson that the drug was dangerous, they were often immediately shut out of Jackson’s inner circle as he sought the drug through other means, they said.

Aside from Jackson’s physical condition and medical history, much of the testimony centered on financial details of his career, to determine damages. Even the driest contractual details revealed in court, however, showed how exceptional Jackson had been in the music business. While major tours often include physical trainers or masseurs to attend to a star, A.E.G. Live executives testified that they had never seen a deal like Jackson’s, which involved a personal doctor to attend him at all times.

Lawyers for the Jacksons pointed to A.E.G. Live’s negotiations with Dr. Murray as evidence that the company effectively had hired the doctor, for $150,000 a month. A.E.G. Live countered that Jackson had hired Dr. Murray and that any payments would have been advances against Jackson’s earnings for the tour. (The company never paid him.)

Complicating the question of who hired the doctor, drafts of a contract were signed by Dr. Murray but not by other parties, including Mr. Jackson. A paragraph of the contract stipulated that the deal would not take effect without Jackson’s signature, but Brian J. Panish, a lawyer for Mrs. Jackson, argued that the document only reinforced an earlier oral contract between Dr. Murray and A.E.G. Live.

Jens Erik Gould contributed reporting.

A version of this article appears in print on October 3, 2013, on Page B1 of the New York edition with the headline: Jury Clears Promoter In Death Of Pop King. Order Reprints|Today's Paper|Subscribe